Thermostatic switch



P 1934- w. G. HARTWIG THERMOSTATIC SWITCH FiledzApril 6, 1933 2 Sheets-Sheet l 555. a: 71:5. ilk

Sept. 4, 1934. w. G. HARTWIG THERMOSTATIC SWITCH 2 SheetsSheet 2 Filed April 6, 1933 QQN GN NQN Patented Sept. 4, 1934 PATENT OFFICE THERMOSTATIC SWITCH William G. Hartwig, Chicago, Ill., assignor to Railway Utility Company, Chicago, 111., a corporation of Illinois Application April 6, 1933, Serial No. 664,687

13 Claims.

This invention relates to a thermostat which, by continued movement of the heat-responsive element, will successively close a plurality of electric circuits and produce a modulated control over a mechanism such as a fuel burner, or a series of individual controls over as many different burner units of a battery of burners, or merely produce a visible effect by the closing of each circuit and thereby signal the status of the thermostat.

The invention proceeds upon the principle of having a group of terminals, one for each circuit, located in the path of a circuit closing contact which is actuated by the heat-responsive element and is so constructed that it encounters the circuit terminals successively by continued movement in the circuit closing direction and releases said terminals successively by its movement in the circuit opening direction.

Another feature of the invention proceeds upon the principle of having one lever uniformly controlled by a thermostat and of varying the relation of another lever during the contacts to said first named lever according to the temperature at which it is desired that the contacts shall open.

Another feature of the invention resides in a novel construction and combination of elements through means of which the aforesaid operative principles may be put into use, and one embodiment thereof is shown in the accompanying drawings by way of illustration.

Still another aspect of the invention proceeds upon the principle of altering the adjustment by an electric motor which may be controlled from a remote point.

With these and various other objects in view, the invention may consist of certain novel features of construction and operation, as will be more full described and particularly pointed out in the specification, drawings and claims appended hereto.

In the drawings, which illustrate an embodiment of the device, and wherein like reference characters are used to designate like parts,

Figure 1 is a front elevation of the complete thermostat; v

Figure 2 is a longitudinal vertical sectional view through the thermostat;

Figure 3 is a fragmentary sectional view along the line 33 of Figure v2 rotated ninety degrees to make the axes of rotation horizontal;

Figure 4 is a view corresponding to Figure 1 but with the cover removed; I

Figure 5 is a section taken mainly along the line 5-5 of Figure 2, rotated ninety degrees to correspond with Figure 3;

Figure 6 is a rear view mainly in elevation taken along the line 66 of Figure 2;

Figure 7 is a fragmentary view substantially along the line '77 of Figure 2;

Figure 8 is a sectional view taken along the line 8-8 of Figure 4; and

Figure 9 is a fragmentary detail view showing the cooperation of the adjustment levers.

Although my invention may take many forms, only one has been chosen for illustration. In this form the numeral 2 designates the main support plate to which may be secured the outer case 4 having thereon a thermometer 6. The main support plate 2 may be secured to a wall box or any other convenient mounting, as by means of screws 10 and spacer bushings 12. It may be noted that in general, the means of supporting the support plates with respect to one another have been omitted for the sake of clarity. Such means would usually consist of an arrangement similar to screw 10 and bushing 12. The outer cover 4 may be screwed by means of screws 14 screwed into an upturned lug 16 on the main support plate.

A thermostat table 18 may be mounted on the main plate 2, as by means of four screws 20 which have been indicated in Figure 4, and which would be augmented by suitable spacer bushings. Said thermostat may conveniently include an outer shell 24, an annular base plate 25 and inner bellows type of diaphragm 26 forming a sealed chamber therein, i. e. between the shell 24 and the diaphragm 26. Because of the character of the contacts, it is preferred that the thermostat diaphragm have a comparatively large pressure surface, so that the actuating force will be relatively great, and will not be unduly affected by slight variations of contact pressure. It is for this reason that a fluid-vapor thermostat is preferred to an expanding metal or bi-metallic thermostat. The bellows 26 is provided with a stem 28 which extends through large concentric holes in base plate 25 and thermostat table 18 carries a needle point 30 bearing in a socket in an adjustment screw 32. The screw 32 transmits the thrust to the bar 34 which for convenience may be called the main bar. This bar carries on its end a forked fulcrum block 36 which rests against a forked fulcrum knife 38 which is rigidly secured to the main plate 2. The other end of the main bar 34 is pressed against a spring 40, the tension of which may be adjusted by screw cap 41. This mounting is dependable and yet substantially frictionless. Pivoted to the bearing block 36 by spindle 43 is a lug 44 which is rigidly secured to the lever 46, which for convenience will be called the contact lever. This contact lever 46 is therefore pivotally mounted on the main bar 34, and may be pivoted with respect thereto by pivoting the lug 44. This is done by means of a pivoted cam lever 48 having formed therein a cam slot 49, the upper edge of which is cam shaped and engages the lug 44. Normally the lug 44 is pressed firmly against the cam surface by a light spring 4'7. The cam lever 48 is pivoted by pin 50 to the main bar 34, preferably being separated therefrom by a bushing 51. The lever 48 is provided with a slot 52 into which a pin 53 fits just loosely enough to avoid friction. The pin 53 is rigidly mounted on an adjsutment lever 54 which may have an upturned end 55 acting both as an indicator and a handle. This end 55 protrudes through main plate 2, a slot and scale being provided as shown.

Carried by the contact lever 46 and preferably insulated therefrom is a rigid contact strip 58. The contact strip 58 may carry a plurality of contacts 60 each positioned to meet a contact 62, each of which contacts 62 is mounted on a spring contact strip 64 but insulated from the other contacts 62 and their circuits. The movement of contact 62 toward the contacts 60 is positively limited by a bushing 66 which may be adjustable if desired. The spring strip 64 presses against bushing 66 which is secured to the contact block 68 preferably formed of insulating material.

Each of theyspring strips may be connected as by a connector bar 70, with an anchor block 72 to another side of which a wire '74 may be secured, as by a screw '75. chor block could be extended and connected directly to the spring strip. The contact block 68 rests against the main plate 2 and may be secured thereto as by screws 77. From Figure 5 it is seen that there are four insulated anchor blocks 72 corresponding to the four contacts, thereby avoiding the necessity ofpassing the corresponding wires through the plate 2, and at the'same time provides a firm anchorage for the screws '75. The contact strip 58 is connected by a flexible wire '78 to a connection plate '79, to which may also be attached the current supply wire 80,- for all of the contacts. To prevent external vibrations from setting up vibration in the contact lever 46, a vibration deadener may be provided. This deadener may take the form of a freely pivoted pendulum-like lever 81 which may be suspended from pivot 82 in a bracket 83 secured to the contact block 68. The period of vibration or swinging of the pendulum 81 is preferably different from the period of vibration of the'contact lever 46 to avoid any danger of their vibrating in unison.

A statement of the operation of the thermostat may make the foregoing description more clear. As the temperature of the room rises the liquid in the thermostat 24 vaporizes, increasing the pressure against the inner face of bellows 26, pressing the plunger 28 'to the left (Figure 2) and rocking the main bar 84 in a counter-clockwise direction about the knife fulcrum 38. This movement is opposed by the spring 40. As the main bar 34 moves in this counter-clockwise direction it moves the contact lever 46 with it, the two being normally maintained substantially rigid with respect to one another by the lug 38 and the spring 47. This movement of the contact lever 46 successively separates the contacts 60 from their corresponding contacts 62, thereby successively Of course the -an-' breaking the circuits through the wires '74 as they are respectively controlled by the contacts 62. As each circuit is broken it may decrease the amount of heat being supplied, or may flash a visual indication, or perform any other functions that it may be desired to control by ,the temperature. As the temperature surrounding the thermostat drops, the thermostat is cooled, the vapor therewithin condenses, decreasing the pressure of the bellows 26, reversing the movement just described, so that the contacts 62 are successively closed by the contacts 60, successively completing the circuits, including wires 74, and successively increasing the heat supply, if that is the function of the thermostat. When the contacts have all been closed, if the thermostat is further cooled, the contact strip 58 will eventually reach the limit of its movement, and spring 4'7 will then yield to permit main bar 34 to continue its movement. The spring 40 should be strong enough to take up all slack and to compress spring 47. The contact lever 46 should be substantially rigid, and the spring 47, though not strong enough to materially bend lever 46, should be strong enough to hold it in such position that lug 44 is firm against its cam surface, unaffected by contact pressure of contacts 62, until all four of these contacts have been closed.

The contacts 62 are preferably so nearly the same length that they are closed by the contacts 60 with only a fraction of a decrease of separation between the closing of the various contacts, though of course any desired gradient may be provided. In assembly, the cap 41 is screwed to about mid-position, and the screw 32 is then adjusted until the contact strip 46 is near its proper position, close to the contacts if the temperature is about seventy degrees Fahrenheit. The exact adjustment to correspond with the calibrations is then made with cap 41.

When temporary adjustment is desired, it may be made for the entire group of contacts by means of the adjustment lever 54 and its handle 55. When this handle, which also is a pointer, is shifted to the right, as seen in Figure 1, it re tates the adjustment lever 48 to the right as seen in Figure 5, thereby thrusting the lug 38 upward. This draws the contact lever 46 further from the main bar 34 so that it will close the contacts at a higher temperature than that at which they would have ,been closed before the adjustment.

Time adjustment control Means is also provided for shifting the lever 54 automatically, and thereby automatically adjusting the thermostat for day and night temperatures. The force for moving adjustment lever 54 is supplied by the motor 86 which turns a pinion 88, which through the reduction gears 89 and 90 rotates a shaft 91 to which is keyed the shifidisk 92. The shift disk 92 bears a pin 93 which engages the arm 94 on shift lever 95, or the arm 96 on shift lever 97. Connections for the motor are such as to cause it to rotate the shift disk 92'one-half revolution every morning and every night, as is described below. For the morning change the pin 93 will be initially in the position shown in Figure 7. As it rotates through the half revolution, it will engage the arm 94 and will swing the shift lever 95 to approximately the position shown in dotted lines. The shift lever 95 is provided with an upstanding lug 98 which strikes the adjustment lever 54 and shifts the same to theposition shown in dotted lines in Figure 7. As the shift disk 92' completes its half revolution, the pin 93 clears the ,arm 94 and permits the shift lever 95 to be swung back to the position shown in full lines, a spring 99 being provided for this purpose.

In the evening, when the motor causes the shift disk 92 to rotate another half revolution,

the pin 93 engages the arm 96 on the shift lever 97, which lever is provided with a lug 100, and swings this lever to the left until the lug 100 engages the adjustment lever 54 and shifts it the desired amount to the left. Again as the shift disk 92 completes its half revolution, the pin 93 passes clear of the arm 96, releases the shift lever 97 which swings back to the position shown, the spring 101 being provided for this purpose. When the shift levers 95 and 97 are in the position shown, i. e., all the time except during the few seconds consumed in the shift, the adjustment lever 54 may be freely adjusted by hand to any position. v

The positions to which the shift levers 95 and 97 shift the adjustment lever 54 may be controlled by regulating the longitudinal position of these shift levers. For this purpose, the shift lever 95 is pivoted by a pin 103 to a crank arm 104, and the shift lever 97 which is pivoted at 106 to a slide 107 is similarly controlled by a crank arm 109 through a connecting rod 111 which is pivoted to crank arm 109 by a pin 112, the other arm on each of the cranks 104 and 109 being formed'as an arcuate-shaped rack 114 each of which is engaged by a worm gear 116 carried by bracket 118. The'cranks having arms 104 and 109 are pivoted to spindles 119. The worm gears 116 may be rotated by the handles 120. The pivot pins 103 and 112 may be provided with upstanding indicator pins 122 to show the temperatures for'which the shift levers are set. For this purpose scales may be provided adjacent the path of the pins, as shown in Figures 1 and 4, and of course slots should be provided in the main plate 2 through which the pins will project or be visible.

The motor .86 is controlled primarily from a clock 123 which may be located remotely, as adjacent the furnace. This clock may be of a kind now purchasable on the open market, and therefore need not be described in detail. It is diagrammatically illustrated in Figure 2, in which 125 represents a contact having a twenty-four hour cycle. However, it should be a clock which completes a circuit through one wire in the morning and through a different wire in the evening, the times for completing these circuits being preferably adjustable. For the purpose of describing this invention, it is sufficient to say that in the morning current is supplied to the wire 124 and at night it is supplied to the wire 126. As shown in Figure 6, the wire 124 is connected to a spring contact 128 and the wire 126 is connected to a spring contact 130. Between these two contacts is an additional spring contact 132 which is connected to the motor 86. The other motor wire 131 is of course connected to the same source of current to which wires 126 and 124 may be connected, for example the transformer coil 133. Sliding in contact with the contact 132 is a switch blade 134 which may be shifted to also contact either contact 128 or contact 130, always connecting one or the other of said contacts to motor contact 132. When current is first supplied to wire 124, blade 134 would be in the position shown in Figure 6, there by completing the circuit to the motor. As the motor operates it will turn the shift disk 92 and the gear wheel 90 as previously described. Mounted eccentrically on the gear 90 is a switch pin 136 which engages a cam ring 138 in which the switch blade 134 is mounted. As the switch pin 136 rotates it has no effect until it reaches the shoulder 140 of the cam ring. When it strikes this shoulder it shifts the cam ring to the left, thereby shifting the switch blade 134 into contact with the contact 130 and out of contact with the contact 128. When the blade 134 leaves contact 128 the circuit to the motor is broken and the motor stops. However, the blade 134 has already contacted contact 130 and connected it with the motor, so that when the clock or other device connects wire 126 to the source of current, the motor is again started and its operation continues until the pin 136 strikes the shoulder 142 and shifts the switch blade 134 back to the position shown.

Of course, it should be obvious that if desired, the adjustment lever 54 could be shifted automatically in some other manner, as by providing a clock adjacent thereto together with suitable connections old in the art. The present system has the advantages of compactness, of requiring no attention whatever, and of leaving the adjustment lever 54 free for manual control all the time except for the second or so consumed in its automatic shift.

It is to be understood that many other embodiments of the invention, including some in improved form, will be apparent, and in the course of time more will be devised by those skilled in the art. It is not desired that this invention be limited to the details described, for its scope includes all such forms or improvements as come within the spirit of the following claims, construed as broadly as the prior art will permit.

What is claimed is:

1. A multiple circuit thermostat for successively closing a plurality of circuits comprising: a heat-responsive member expansible by heat, a

pair of relatively movable members controlled by said heat-responsive member, a plurality of contacts for the various circuits on said relatively movable members, the contacts of the various circuits being closed successively by the movement of the movable one of said relatively movable members, said movable member being moved by said heat-responsive member through a lever system in which one lever is substantially rigid and is operated by the heat-responsive member, and the other lever is substantially rigid but connected to said first named lever through a lost- .motion connection permitting a continued movement of said first named lever after the other lever has reached the limit of its movement.

2. A multiple circuit thermostat for successively closing a plurality of circuits comprising: a.

heat-responsive member expansible by heat, a pair of relatively movable members controlled by said heat-responsive member, a plurality of contacts for the various circuits on said relatively movable members, the contacts of the various circuits being closed successively by the movement of the movable one of said relatively movable members, said movable member being moved by said heat-responsive member through a lever system in which one lever is substantially rigid and is operated by the heat-responsive member,

and the other lever is substantially rigid but connected to said first named lever through a lostmotion connection permitting a continued movement of said first named lever after the other lever has reached the limit of its movement, and

a'spring resisting such lost motion with sufficient force not to be substantially affected by the contact pressure but without enough force to materially flex said levers.

3. A multiple circuit thermostat for succes-.

sively closing a plurality of circuits comprising: a heat-responsive member expansible by heat, a pair of relatively movable members controlled by said heat-responsive member, a plurality of contacts for the various circuits on said relatively movable members, the contacts of the various circuits being closed successively by the movement of the movable one of said relatively movable members, said movable member being moved by said heat-responsive member through a lever system in which one lever is substantially rigid and is operated by the heat-responsive member, and the other lever is substantially rigid but connected to said first named lever through a lost-motion connection permitting a continued movement of said first named lever after the other lever has reached the limit of its movement, a spring resistingsuch lost motion with sumcient force not to be substantially affected by the contact pressure but without enough force" to materially flex said levers, and means to adjust the relation of said levers.

4. A multiple circuit thermostat for successively closing a plurality of circuits comprising: a heat-responsive member expansible by heat, a pair of relatively movable members controlled by said heat-responsive member, a plurality of contacts for the various circuits on said relatively movable members, the contacts of the various circuits being closed successively by the movement of the movable one of said relatively movable members, said movable member being moved by said heat-responsive member through a lever system in which one lever is substantially rigid and is operated by the heat-responsive member, and the other lever is substantially rigid but connected to said first named lever through a lost-motion connection permitting a continued movement of said first named lever after the other lever has reached the limit of its movement; said levers being suspended as a unit between-a knife-edge fulcrum, a pointed pressure member, and a spring.

5, A multiple circuit thermostat for successively closing a plurality of circuits comprising: a heat-responsive member expansible by heat, a pair of relatively movable members controlled by said heat-responsive member, a plurality of contacts for the various circuits on said relatively movable members, the contacts of the various circuits being closed successively by the movement of the movable one of said relatively movable members, said movable member being moved by said heat-responsive member through a movement-increasing lever; and a vibration dampener associated with said lever comprising a pendulum resting against said lever and having a different frequency of vibration than said lever.

6. A multiple circuit thermostat for successively closing a plurality of circuits comprising: a heat-responsive member expansible by heat, a pair of relatively movable members controlled by said heat-responsive member, a plurality of contacts for the various circuits on said relatively movable members, .the contacts of the various circuits being closed successively by the movement of the movable one of said relatively movable members, said movable member being moved by said heat-responsive member through a lever system which is normally substantially inflexible but in which is included a lost motion connection whereby said heat-responsive member may continue its movement when said movable member reaches the limit of its movement; the heatresponsive member and the lever system being so forceful, and the contact pressure between the relatively movable members being so minute that the latter has substantially no effect on the movement of said movable member.

'7. A multiple circuit thermostat for successively closing a plurality of circuits comprising: a heat-responsive member expansible by heat, a pair of relatively movable members controlled by said heat-responsive member, a plurality of contacts for the various circuits on said relatively movable members, the contacts of the various circuits being closed successively by the movement of the movable one of said relatively movable members, said movable member being moved by said heat-responsive member through a lever system which is normally substantially inflexible; the heat-responsive member being of the liquid vapor type, having a large size pressure surface and a strong counterspring; and said heat-responsive member and said lever system exerting tact pressure during the closing of the contacts being so minute, that the latter has substantially no effect on the thermostat movements.

8. The combination of a thermostat and automatic adjustment means therefor including: an adjustment lever on said thermostat, a pivoted shift lever engageable with said adjustment lever but normally biased to a position of non-engagement, and means for shifting said shift lever to engage and shift said adjustment lever.

9. The combination of a thermostat and automatic adjustment means therefor including: an adjustment lever on said thermostat, a pivoted shift lever,,engageable with said adjustment lever but normally biased to a position of non-engagement, and means for shifting said shift lever to engage and shift said adjustment lever; said means for shifting including a revolving pin arranged to engage said shift lever through a part of its revolution.

10. The combination of a thermostat and automatic adjustment means therefor including: an adjustment lever on said thermostat, a pivoted shift lever engageable with said adjustment lever but normally biased to a position of non-engagement, and means for shifting said shift lever to engage and shift said adjustment lever; the angular duration of said engagement being adjustable and governing the position to which said adjustment lever has shifted.

11. The combination of a thermostat and auto: matic adjustment means therefor including: an adjustment lever on said thermostat, shift means for shifting said adjustment lever in both directions alternately, power means for operating said shift means, and control means for stopping said power means when it has operated said shift means in one direction, and for preparing said power means to be operated again under the proper external influence.

12. The combination of a thermostat and automatic adjustment means therefor including: an adjustment lever on said thermostat, shift means for shifting said adjustment lever in both directions alternately, power means for operating said shift means, and control means for stopping said power means when it has operated said shift means in one direction, and for preparing said power means to be operated again under the let 100 such force on said movable member, and the conproper external influence; said power and control means including an electric motor having two current supply wires interchangeably connectible thereto in addition to a common return wire, and a switch operable by the motor for switching the connection of said motor from one to the other of said supply wires.

13. The combination of a thermostat and automatic adjustment means therefor including: an adjustment lever on said thermostat, shift means for shifting said adjustment lever in both directions alternately, power means for operating said shift means, and control means for stopping said power means when it has operated said shift means in one direction, and for preparing said power means to be operated again under the proper external influence; said power and control means including an electric motor having two current supply wires interchangeably connectible thereto in addition to a common return wire, and a switch operable by the motor for switching the connection of said motor from one to the other of said supply wires; and means for supplying current to one supply wire at one time for a period long enough for said motor to efiect said switching from said wire to the other wire, and for subsequently supplying current to said other wire long enough for said motor to eifect the switching back to the original connection.

WILLIAM G. HARTWIG. 

